5 Answers
5

Yes to both as Lauren said, and once you train the reader that you're a nice author who doesn't ever violate "One speaker per line" and sticks to that while mixing emotes and actions in too, you may go with a third form which is then even more smooth:

"..." X did this, "..."

Take:

Kim shook his fist and muttered, "Not you too, bastard!"
"So..." Josh raised his gun and said, "are we going to do it the easy way?"

versus

Kim shook his fist. "Not you too, bastard!"
"So..." Josh raised his gun. "Are we going to do it the easy way?"

It's the actions that describe the speaker, and you kill two birds with one stone, give variety against "he said, she said" and get the scene to live for real.

I use non-conversation bits to show where pauses or lulls in the conversation occur. They can be short, like:

"Hey," said Bob.

"Hey yourself."

"So..." Bob started and then cleared his throat. This was only my third week on the job but I knew even at that early date that when Bob cleared his throat, he had something truly stupid to say. "Do you have those TPS reports?"

I stared at Bob incredulously. What did he think this was, Office Space? "No, Bob, I do not have them. Perhaps they got lost in the year 1998."

Hopefully that first one demonstrated a little awkward pause while the main character thought up a (semi) witty response. You can also make them longer:

"Nancy, what do you think of the global dilemma?"

Patricia was always asking Nancy stupid questions like this. She was soooo dumb. If she really wanted an answer, couldn't she just look it up on like Wikipedia or something? Maybe she could ask Jeeves. Oh my god! Was Ask Jeeves even still around? Maybe Jeeves had been replaced by a younger, hunkier guy named like Falco or something. No, that was stupid; computers don't get old and only rich guys ever used Ask Jeeves so they'd probably always want some fake old butler dude.

"Nancy, are you even listening to me?"

You can just add he said/she said to the end of each line; in fact, your readers will generally get the hang of it after an exchange or two (especially if your dialogue is strong enough) and you really don't need to add any tags at all. The thing about doing that is, it makes the conversation feel like a high-speed, no-pause madcap comedy style banter (think: Gilmore Girls), and if your characters are just talking about what went on that day at school it's going to feel a bit off. Additionally, there becomes a risk of making the characters seem like disembodied talking heads if you keep it up for too long.

One little trick you can do - that I recommend doing for dialogue in general - is on your subsequent drafts, go in and read it out loud. For one thing, in my experience this really roots out any inauthentic sounding verbiage, sentences that are too long to be said within one breath, and so on. For another, I think that with dialogue in particular you get a pretty good sense of how long those filled pauses occur. In real life, people say "um" and "ah" a lot; readers won't like you to drop those in (unless you want to portray a dullard) but they do kind of expect the "pause" side of the filled pause.

I really love the dialogue in the Guest translation of the Mabinogion, it adds to the feeling that you are reading a text from a different time:

A horseman spoke to Pwyll.
"...," said he.
"...," said Pwyll.
"...," said he.
"...," said he.
"...," said he.
etc.

No variation, and only the first speaker is named, the following turns are all not identifed.

It won't help you write good dialogue today, but it shows that there is not one single genre of fiction with universal rules, and that maybe sometimes a bit of courage to find your own style of writing will make your book stand out and prevail among a host of formulaic bestseller clones.

And as he was setting on his dogs he saw a horseman coming towards him upon a large light-grey steed, with a hunting horn round his neck, and clad in garments of grey woollen in the fashion of a hunting garb. And the horseman drew near and spoke unto him thus. "Chieftain," said he, "I know who thou art, and I greet thee not." "Peradventure," said Pwyll, "thou art of such dignity that thou shouldest not do so." "Verily," answered he, "it is not my dignity that prevents me." "What is it then, O Chieftain?" asked he. "By Heaven, it is by reason of thine own ignorance and want of courtesy." "What discourtesy, Chieftain, hast thou seen in me?" "Greater discourtesy saw I never in man," said he, "than to drive away the dogs that were killing the stag and to set upon it thine own. This was discourteous, and though I may not be revenged upon thee, yet I declare to Heaven that I will do thee more dishonour than the value of an hundred stags." "O Chieftain," he replied, "if I have done ill I will redeem thy friendship." "How wilt thou redeem it?" "According as thy dignity may be, but I know not who thou art?" "A crowned king am I in the land whence I come." "Lord," said he, "may the day prosper with thee, and from what land comest thou?" "From Annwvyn," answered he; "Arawn, a King of Annwvyn am I." "Lord," said he, "how may I gain thy friendship?" "After this manner mayest thou," he said. "There is a man whose dominions are opposite to mine, who is ever warring against me, and he is Havgan, a King of Annwvyn, and by ridding me of this oppression, which thou canst easily do, shalt thou gain my friendship." "Gladly will I do this," said he. "Show me how I may." "I will show thee. ...

The second example just inserts the tag in the middle of speech, which is fairly standard if redundant. The first example though...

If you're asking for the reason for this ordering - it's a matter of personal style. In literary writing it feels awkward and is rarely used... mostly by unskilled authors, because they don't know any better.

Now first, why they (the unskilled authors) write it like that, and when would skilled authors use this is how natural speech follows:

So, I went to Lucy and she said 'Mary has the keys'

You told me "It's not important."

He said "Yes".

You said it's here.

Contrast it with what you'd find in books:

I went to Lucy and asked her. "Mary has the keys," she answered.

"It's not important," you tell me.

"Yes", he said.

It was supposed to be here, according to what you said.

If, in normal conversation, you report someone's speech, you first identify the speaker, then follow up either with the quote or a paraphrase. So, if you want to create this impression - of the narrator talking directly to the reader, then you'll use this ordering. It contrasts standard literary narration with conversational tone, removes the impersonal distance of the narrator.

Yes to both. Repetitive sentence structure grates on the ear. Also, sometimes it helps to clarify the speaker before the dialogue, and sometimes you actually want action or a pause to occur before the speech, but not separate from it.